1. Field of the Invention
The present invention relates to a sheet processing apparatus that processes a sheet, such as a sheet of paper, to an image forming apparatus that includes the sheet processing apparatus, and to an image forming system.
2. Description of the Related Art
A conventionally-known image forming system includes a sheet processing apparatus in which a sheet fastening apparatus is provided to perform an operation to fasten a bundle of sheets that have images formed by an image forming apparatus.
In a sheet processing apparatus disclosed in Japanese Patent Application Laid-open No. 2010-274623, a sheet fastening apparatus that has a pressing fastener system is provided to fasten a bundle of sheets, without using metallic staples, by strongly nipping the bundle of sheets by using a pair of pressing fastener teeth that are pressing fastener members that have concavity and convexity so that the fibers of the sheets are tangled and the sheets are pressed to be fastened. Pressure fastening, i.e., fastening a bundle of sheets without using metallic staples, can eliminate the trouble in removing the metallic staples from the bundle of sheets when the bundle of sheets is disposed of or is put into a shredder.
In the sheet processing apparatus disclosed in Japanese Patent Application Laid-open No. 2010-274623, after an image is formed on a bundle of sheets, the bundle of sheets is conveyed into a gap between one of the pressing fastener teeth and the other one of the pressing fastener teeth in the sheet fastening apparatus. Next, the one of the pressing fastener teeth is moved toward the bundle of sheets so that the bundle of sheets is pressed by the pair of pressing fastener teeth and the bundle of sheets is fastened. Then, after the one of the pressing fastener teeth is moved in a direction away from the bundle of sheets, the bundle of sheets is conveyed toward a discharge tray and is discharged onto the discharge tray.
However, a large pressing force is required to strongly nip a bundle of sheets by using a pair of pressing fastener teeth that has concavity and convexity. Therefore, a problem occurs in that, after a bundle of sheets is fastened by pressure, the bundle of sheets adheres to the one of the pair of pressing fastener teeth that does not move in a direction away from the bundle of sheets after the fastening operation is performed. If the bundle of sheets is conveyed toward the discharge tray while the sheet adheres to the pressing fastener tooth, there is a possibility that a problem occurs, such as a conveyance failure or damage to the sheet.
In consideration of the above, there is a need to provide a sheet processing apparatus, an image forming system that includes the sheet processing apparatus, and an image forming apparatus that make it possible to prevent a conveyance failure or damage to a sheet.